the power, P = I^2 * R = (V^2)/R

but what is R? we can find it using ohms law

V = IR

=> R = V/I = 120/1.2 = 100

=> P = (V^2)/R = (120^2)/100 = 144 watts

P = (V^2)/R

Also, what current flows through a 75W bulb connected to a 120 V outlet?

=> 75 = (120^2)/R

=> R = (120^2)/75 = 192 ohms

Now V = IR

=> I = V/R = 120/192 = 0.625 amps

or we could have found I directly, without first finding R:

P = (I^2)*R

since V = IR => R = V/I

so P= (I^2)(V/I) = IV

=> I = P/V = 75/120 = 0.625